Swivel joint

ABSTRACT

A swivel joint for the interconnection between pipes on an upper structure side and a lower structure side of a construction equipment of the upper structure revolving type. The swivel joint has formed therein a fluid passage for fuel supply oil to be supplied from a fuel oil tank on the lower structure side to an engine on the upper structure side and another fluid passage for return oil to be returned from the engine to the tank. The fluid passages are formed in an isolated condition from an other fluid passage so that fuel supply oil or return oil may not be mixed with any other fluid within the swivel joint or may not leak to the outer side of the swivel joint. 
     Another swivel joint is also disclosed wherein a body is divided in an axial direction into two parts. One the body parts is formed from a non-ferrous metal material having an anticorrosion property so that the body may not suffer from corrosion by fuel oil or air which contains water therein, and passages and annular grooves for fuel oil and air are formed in the anticorrosion body part.

This is a continuation of application Ser. No. 07/510,849, filed on Apr.18, 1990 now U.S. Pat. No. 5,104,154.

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT

This invention relates to a swivel joint for use with a constructionequipment of the upper structure revolving type such as a wheel mountedshovel or a wheel crane for connecting fluid pipes to each other betweenlower structure and an upper structure.

The prior art will be described taking a wheel mounted shovel as anexample of a construction equipment of the upper structure revolvingtype.

Referring to FIG. 4, a conventional wheel mounted shovel shown includesa lower structure 1 serving as a lower base and an upper structure 2carried on the lower structure 1 by way of a pivotal bearing 3, and anengine 4, a tank 5 for working fluid to be supplied to hydraulic devicesand a tank 6 for fuel oil to be supplied to the engine 4 are installedon the upper structure 2.

FIG. 5 shows a fuel oil circuit interconnecting the fuel oil tank 6 andthe engine 4.

Fuel oil in the fuel oil tank 6 is supplied into a nozzle holder 9 by afeed pump 7 and an injection pump 8 as indicated by solid line arrowmarks in FIG. 5. Meanwhile, return oil which overflows from the engine 4is returned into the fuel oil tank 6 by way of a filter 10 as indicatedby broken line arrow marks.

Additionally FIG. 6 shows a construction of a conventional swivel joint.

The swivel joint 11 shown includes a tubular body 12 and a cylindricalstem 13 fitted for rotation relative to each other around a common axis,and for example, the stem 13 is mounted as a rotary side member on theupper structure while the body 12 is mounted as a fixed side member onthe lower structure.

The body 12 is divided in the direction of the axis thereof into twodivisional parts including a first divisional body part 14 and a seconddivisional body part 15 in order to facilitate working and assembly ofthe swivel joint. The two body parts 14 and 15 are connected in anintegrated relationship to each other by means of bolts 16.

A stem side air passage 17a and a stem side working oil passage 18a areprovided in the stem 13.

Meanwhile, a pair of body side air and working oil passages 17c and 18cand a pair of body side annular grooves 17b and 18b are provided in thebody 12. A pair of air and working oil passages 17 and 18 are thusprovided which extend through the body 12 and the stem 13. A pluralityof seal members 19 are provided on an inner periphery of the body 12.

Each of the passages 17 and 18 has an end connected to a correspondingpipe not shown on the upper structure 2 side and the other end connectedto another corresponding pipe not shown on the lower structure 1 sidesuch that the upper and lower pipes for air and the upper and lowerpipes for working oil may be interconnected by way of the swivel joint11.

It is to be noted that, while such passages 17 and 18 as described aboveare normally provided each by a plural number, only one of each of themis shown to facilitate illustration and description of the mechanism.

Such a wheel mounted shovel is disadvantageous in that, where the fueltank 6 is mounted on the upper structure 2 as described above, it islocated at an excessively high position, and consequently, a fuel oilsupplying operation is cumbersome.

Thus, it may seem convenient to install the fuel oil tank 6 otherwise onthe lower structure 1 as shown in FIG. 7 in order to facilitate such afuel oil supplying operation.

In this instance, a fuel oil supplying pipe for supplying fuel oil fromthe fuel oil tank 6 to the engine 4 and a return oil pipe for returningreturn oil to the tank 6 are each divided into upper and lower portionssimilarly to any other pipe for other fluid such as air and working oil,and the upper and lower portions of the pipes are connected to eachother by way of the swivel joint 11. In this instance, if theconstruction of the fuel oil passages of the conventional swivel joint11 is employed as it is as passage construction for fuel oil, then thiswill give rise to the following problem.

In particular, in a swivel joint of the type mentioned, fluid is likelyto leak from an annular groove at a junction between fluid passages ofthe body side and the stem side to a location between fitting faces ofthe body and stem, and this leaking fluid may be mixed with anotherleaking fluid or may leak to the outer side.

Accordingly, where such a construction is employed that fuel oil (fuelsupply oil and return oil) is delivered between the body and the stem byway of an annular groove in the body similarly as for air and workingoil, such other fluid as air or working oil may be mixed with the fueloil thereby to deteriorate the combustion efficiency, or on thecontrary, fluid oil may be mixed into some other fluid thereby toobstruct an original function of the fluid. Or there is a problem thatfuel oil may leak to the outer side to bring about a dangerouscondition.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a swivel joint whichovercomes such a drawback as described above.

In order to attain the objects, according to one aspect of the presentinvention, there is provided a swivel joint for a construction equipmentor the like wherein an upper structure on which an engine is carried ismounted for swinging movement on a lower structure on which a fuel oiltank is disposed, which comprises a body secured to one of the upper andlower structures, and a stem secured to the other of the upper and lowerstructures and fitted for relative rotation in an inner bore of the bodyaround a common axis, the stem having a fuel oil supply passage formedtherein along the axis thereof for supplying fuel oil from the fuel oiltank to the engine therethrough, the stem further having a stem sidereturn oil passage formed therein which forms part of a return oilpassage for returning fuel oil from the engine to the fuel oil tank, thebody having a body side return oil passage formed therein, the bodyfurther having a return oil annular groove formed therein forcommunicating the body side return oil passage with the stem side returnoil passage, the body further having a drain oil annular groove formedtherein for catching return oil leaking from the return oil annularpassage, the stem further having a drain oil passage formed therein forcommunicating the drain oil annular passage with the fuel oil tank.

With this swivel joint, since fuel supply oil is supplied toward theengine in an isolated condition from any other fluid by way of the fuelsupply oil passage extending along the axis of the stem, there is nopossibility that such fuel supply oil may be mixed with any other fluidor may leak to the outer side of the swivel joint.

Regarding the return oil, even if return oil leaks out from the returnoil annular groove, it will be caught by the drain oil annular grooveand returned into the tank by way of the drain oil passage.Consequently, return oil is prevented from mixing with any other fluidand from leaking to the outer side of the swivel joint similarly to fuelsupply oil.

Further, where the passage for fuel supply oil in the swivel joint isconstituted only from a single pipe member, maintenance of the fuel oilsupply circuit such as inspection or repair can be performed readily.

A pair of such drain oil annular grooves may be formed at locations ofthe body on the opposite sides of the return oil annular groove in theaxial direction so that, in case return oil leaks in either of theopposite directions of the axis from the return oil annular groove, itmay be caught with certainty by the drain oil annular grooves.

Preferably, a seal member is disposed on an inner periphery of the bodybetween the return oil annular groove and the drain oil annular grooveor either one or each of the drain oil annular grooves. Thus, leakage ofreturn oil is prevented by a sealing action of the seal member, and onlyreturn oil which passes the seal member is caught by the drain oilannular groove. Consequently, such a situation can be prevented thatleaking return oil may not be caught by the drain oil annular groove andmay reach an annular groove for any other fluid.

According to another aspect of the present invention, there is provideda swivel joint for construction equipment or the like wherein an upperstructure on which an engine is carried is mounted for swinging movementon a lower structure on which a fuel oil tank is disposed, the swiveljoint having several fluid passages formed therein which include an airpassage and a fuel oil passage which interconnects the fuel oil tank andthe engine, the swivel joint comprising a body secured to one of theupper and lower structures, and a stem secured to the other of the upperand lower structures and fitted for relative rotation in an inner boreof the body around a common axis, the body being composed of a pluralityof divisional parts in the axial direction thereof, a particular one ofthe divisional parts being made of a non-ferrous metal material havingan anticorrosion property, the anticorrosion divisional part of the bodyhaving formed therein body side passages and annular grooves for fueloil and air which make part of the fuel oil passage and air passage,respectively.

One of the other causes of mixture of the different fluids with eachother in a swivel joint and leakage of any fluid to the outer side ofthe swivel joint is damage to a seal member arising from corrosion of abody. In particular, fuel oil and air are originally inclined to acceptwater therein from the outside and besides have no anticorrosionproperty as distinct from working oil. Meanwhile, in the case of theconventional swivel joint 11 shown in FIG. 6, the two divisional parts14 and 15 of the body 12 are both formed from an iron material which islikely to rust. Consequently, if the inner periphery of the body suffersfrom corrosion, then the seal members 19 provided there will be damagesand thus deteriorate a sealing action thereof, which leads to a mixtureof different fluids with each other or leakage of such fluids to theouter side of the swivel joint.

With the swivel joint of the construction according to the second aspectof the present invention described above, however, since corrosion ofthe inner periphery of the body by fuel oil or air which contains watertherein can be prevented, possible damage to a seal member arising fromcorrosion of the inner periphery of the body as well as a mixture ofdifferent fluids with each other and leakage of such fluids to the outerside of the swivel joint which arise from such damage to the seal membercan be prevented.

Preferably, the anticorrosion divisional part of the body has a drainoil annular groove formed on an inner periphery thereof for catchingreturn oil leaking from the annular groove for fuel oil while the stemhas a drain oil passage formed therein for communicating the drain oilannular groove with the fuel oil tank. Thus, fuel oil can be isolatedfrom any other fluid and possible damage to the seal member arising fromcorrosion of the body can be prevented. Consequently, the prevention ofthe mixture of different fluids with each other and of leakage of suchfluids to the outer side of the swivel joint is assured.

Such drain oil annular grooves may be formed in pairs at locations ofthe anticorrosion divisional part of the body on the opposite sides ofthe annular groove for fuel oil in the axial direction.

Preferably, a seal member is disposed on an inner periphery of the bodybetween the annular groove for fuel oil and the drain oil annular grooveor either one or each of the drain oil annular grooves.

The above and other objects, features and advantages of the presentinvention will become apparent from the following description and theappended claims, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view of an entire swivel joint showing apreferred embodiment of the present invention;

FIG. 2 is an enlarge sectional view of part of the swivel joint of FIG.1;

FIG. 3 is a circuit diagram showing general construction of a fuel oilcircuit where the swivel joint of FIG. 1 is incorporated in a wheelmounted shovel;

FIG. 4 is a schematic side elevational view of a wheel mounted shovel ofthe type wherein a fuel oil tank is mounted on an upper structure;

FIG. 5 is a circuit diagram showing general construction of a fuel oilcircuit of the wheel mounted shovel shown in FIG. 4;

FIG. 6 is a vertical sectional view showing a conventional swivel joint;and

FIG. 7 is a schematic side elevational view of a wheel mounted shovel ofanother type wherein a fuel oil tank is mounted on a lower structure.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

An embodiment of the present invention will be described with referenceto FIGS. 1 to 3.

FIG. 3 shows a fuel oil circuit incorporated in a swivel joint 21 towhich the present invention is applied.

The fuel oil circuit has a somewhat similar construction to that of thefuel oil circuit shown in FIG. 5 and described hereinabove, andaccordingly, only differences will be described here to avoidredundancy. In particular, upper and lower pipes for fuel supply oil andreturn oil are connected to each other by way of a fuel supply oilpassage 27 and a return oil passage 28 formed in the swivel joint 21. Adrain oil passage 31 for recovering an internal leak portion (drain oil)of return oil into a tank 6 is also provided in the swivel joint 21.

Detailed construction of the swivel joint 21 is shown in FIGS. 1 and 2.Referring to FIGS. 1 and 2, the swivel joint 21 is composed of a body 22and a stem 23.

The body 22 is divided in a direction of an axis thereof into twodivisional parts including a first divisional body part 24 and a seconddivisional body part 25 similarly to the conventional swivel joint 11shown in FIG. 6 in order to facilitate working and assembly of themechanism. The first divisional body part 24 is mounted on an upperstructure 2 while the stem 23 is mounted on a lower structure (notshown).

The stem 23 has a through-hole 26 formed along an axis thereof, and apipe member 27 serving as a fuel oil supply passage extends through thethrough-hole 26 of the stem 23. The pipe member 27 is connected at anupper end thereof to a fuel oil supply pipe not shown on the upperstructure side and at a lower end thereof to another fuel oil supplypipe not shown on the lower structure side each by way of a rotary jointnot shown so that fuel oil may be supplied from the fuel oil tank 6 ofFIG. 3 to the engine 4 by way of the pipe member 27.

The stem 23 further has stem side fluid passages 28a, 29a and 30a formedtherein for return oil, air and working oil, respectively.

Meanwhile, the first divisional body part 24 which constitutes part ofthe body 22 is formed from an iron material similarly as in the body ofa conventional swivel joint while the second divisional body part 25 isformed from a non-ferrous metal material having an anticorrosionproperty such as aluminum.

A body side working oil passage 30c and a working oil annular groove 30bfor the communication of the passage 30c with the stem side working oilpassage 30a are formed in the first divisional body part 24 of the body22 and generally constitute a working oil passage 30.

Meanwhile, a body side return oil passage 28c and a body side airpassage 29c as well as a return oil annular groove 28b and an airannular passage 29b for the communication of the passages 28c and 29cwith the corresponding stem side fluid passages 28a and 29a,respectively, are formed in the second divisional body part 25 of thebody 22 and generally constitute a return oil passage 28 and a workingoil passage 29, respectively.

Further, a pair of body side drain oil annular grooves 31a and 31b areformed at locations of an inner periphery of the second divisional bodypart 25 on the opposite sides of the return oil annular groove 28b inthe axial direction (at the opposite upper and lower locations) while apair of return oil leakage preventing seal members 32 (FIG. 2) areprovided between the return oil annular groove 28b and the two drain oilannular grooves 31a and 31b.

Meanwhile, the stem 23 has a drain oil passage 31c formed therein forcommunicating the two drain oil annular grooves 31a and 31b with eachother. The drain oil passage 31c is connected to the fuel oil tank 6 byway of a pipe not shown, and a drain oil passage 31 is constituted fromthe drain oil annular grooves 31a and 31b and the drain oil passage 31c.

A plurality of seal members 33 (FIG. 2) are provided at requiredlocations of the inner periphery of the body 22 in addition to the sealmember 32 for the prevention of return oil leakage.

In the swivel joint of the construction described above, fuel oil issupplied from the fuel oil tank 6 to the engine 4 by way of the pipe 27in an isolated condition from any other fluid, and consequently, thereis no possibility that such fuel supply oil may be mixed with any otherfuel nor may leak to the outer side of the swivel joint.

On the other hand, return oil is returned to the fuel oil tank 6 by wayof the return oil passage 28 extending through the body 22 and the stem23 similarly to any other fluid.

In this instance, in case such an accident happens that return oil leaksout from the return oil annular groove 28b to a location between fittingfaces of the second divisional body part 24 and the stem 23, the leakageoil will be prevented from axial permeation or dispersion in the axialdirection by a sealing action of the seal members 32.

Additionally, since the drain oil annular grooves 31a and 31b areprovided on the opposite sides of the return oil annular groove 28b inthe axial direction, even if such return oil that leaks out from thereturn oil annular groove 28b passes either one of the seal members 32,it will be caught by a corresponding one of the drain oil annulargrooves 31a and 31b and returned into the tank 6 by way of the drain oilpassage 31.

On the other hand, since the second divisional body part 25 of the body22 is formed from a non-ferrous metal material having an anticorrosionproperty and the annular grooves 28b and 29b and the passages 28c and29c for return oil and air, respectively, are provided in theanticorrosion divisional body part 25, there is no possibility that thedivisional body part 25, particularly inner periphery portions thereofat which the seal members 32 and 33 are provided, may suffer fromcorrosion by return fuel oil or air which contains water therein.Consequently, possible damage to the seal members 32 and 33 which mayarise from corrosion of the divisional body part 25 is prevented.

It is to be noted that, since the inner periphery of the stem 23 isplated with suitable metal, no corrosion will appear on the innerperiphery of the stem 23. Accordingly, there is no possibility that theseal members 32 or 33 may be damaged due to possible corrosion of thestem side.

Accordingly, with the swivel joint of the embodiment described above, inaddition to the fact that fuel supply oil and return oil are fed in theswivel joint in an isolated condition from any other fluid, mixture offluids with each other and leakage of any fluid to the outer side of theswivel joint can be prevented with certainty.

It is to be noted that, while it may seem convenient to form the firstdivisional body part 24 from a non-ferrous metal material having ananticorrosion property in order to prevent possible corrosion similarlyto the second divisional body part 25, since normally the pressure ofworking oil is very high (350 kg/cm² or so) comparing with the pressureof fuel oil and air (normally 10 kg/cm² or less), it is desirable toform the first divisional body part 24 from a ferrous material having ahigh strength.

MODIFICATIONS

(I) While the swivel joint of the embodiment described above has acombination of the construction wherein the passages for fuel supply oiland return oil are formed in an isolated condition from any other fluidpassage and the construction wherein the body side fluid passages andannular grooves for return oil and air are provided on the anticorrosiondivisional body part, since each of the constructions exhibits by itselfa high effect for the prevention of mixture of different fluids or ofexternal leakage of any fluid, only either one of the constructions maybe employed.

(II) The drain oil annular passage of the present invention need not beprovided on each side of the return oil annular groove in the axialdirection as in the embodiment described above but may be provided, forexample, where leakage of return oil occurs substantially only in aspecific one of the opposite axial directions, only on the specificlocation.

(III) While, in the embodiment described above, the seal members areprovided between the return oil annular groove and the drain oil annulargrooves, even if the seal members are not provided, the swivel joint isstill far more advantageous, due to presence of the drain oil annulargrooves, with regard to the effect of prevention of mixture of fuel oilwith any other fluid and prevention of external leakage of fuel oil,than a conventional swivel joint.

(IV) In the embodiment described above, the passage 28c and the annulargroove 28b for return oil are provided on the anticorrosion divisionalbody part 25 while fuel supply oil is flowed along the pipe member 27disposed in the through-hole 26 extending along the axis of the stem,the reverse construction may otherwise be employed wherein fuel supplyoil is flowed by way of the passage 28c and the annular groove 28b ofthe anticorrosion body part 25 while return oil is flowed along the pipemember 27 in the through-hole 26 of the stem 23.

(V) While in the embodiment described above the swivel joint isdescribed as applied to a wheel mounted shovel, the present inventioncan be applied to any swivel joint which is used in a working machine ofthe upper structure revolving type which is composed of a lower base andan upper revolving structure.

Having now fully described the invention, it will be apparent to one ofordinary skill in the art that many changes and modifications can bemade thereto without departing from the spirit and scope of theinvention as set forth herein.

What is claimed is:
 1. A swivel joint for construction equipment or thelike wherein an upper structure on which an engine is carried is mountedfor swinging movement on a lower structure on which a fuel oil tank isdisposed, said swivel joint having several fluid passages formed thereinwhich include an air passage and a fuel oil passage which interconnectssaid fuel oil tank and said engine, said swivel joint comprising:a bodysecured to one of said upper and lower structures; and a stem secured tothe other of said upper and lower structures and fitted for relativerotation with respect to said body in an inner bore of said body arounda common axis; said body being composed of a plurality of divisionalparts in the axial direction thereof, one of said divisional parts beingmade of an anticorrosive non-ferrous metal material and the other ofsaid divisional parts being formed of a ferrous material, theanticorrosive divisional part of said body having formed thereon atleast one body side passage and at least one annular groove for fuel oiland air which respectively comprise a part of said fuel oil passage andsaid air passage.
 2. The swivel joint according to claim 1, wherein saidanticorrosive divisional part of said body comprises first and seconddrain oil annular groove means for catching return oil leaking from saidat least one annular groove for fuel oil, said first and second drainoil annular groove means each being located, with respect to an axialdirection of said swivel joint, on opposite sides of said at least oneannular groove for fuel oil and being formed on an inner periphery ofsaid body, said stem comprising drain oil passage means forcommunicating said first and second drain oil annular groove means withsaid fuel oil tank, said drain oil passage means being formed in saidstem in fluid communication with both said first and second drain oilannular groove means.
 3. The swivel joint according to claim 2, furthercomprising:a first seal member disposed on an inner periphery of saidanticorrosive divisional part of said body axially between said at leastone annular groove for fuel oil and one of said first and second drainoil annular groove means; and a second seal member disposed on saidinner periphery of said anticorrosive divisional part of said bodyaxially between said at least one annular groove for fuel oil and theother of said first and second drain oil annular groove means.